HBS1L deficiency causes retinal dystrophy in a child and a mouse model associated with defective development of photoreceptor cells.

Inherited retinal diseases encompass a genetically diverse group of conditions caused by mutations in genes critical to retinal function, including handful of ribosome-associated genes. This study focuses on HBS1L gene which encodes for HBS1-like translational GTPase crucial for ribosomal rescue. We have reported a female child carrying biallelic HBS1L variants, manifesting with poor growth and neurodevelopmental delay. Here we describe the ophthalmologic findings in the patient and Hbs1ltm1a/tm1a hypomorph mice and describe the associated microscopic and molecular perturbations. The patient has impaired visual function, showing dampened amplitudes of a- and b-waves in both rod- and cone-mediated responses. Hbs1ltm1a/tm1a mice exhibited profound thinning of the entire retina, specifically of the outer photoreceptor layer, due to extensive photoreceptor cell apoptosis. Loss of HBS1L resulted in comprehensive proteomic alterations on mass spectrometry analysis, with 169 proteins increased and 480 decreased including rhodopsin and peripherin 2. GO biological process and GSEA analyses reveal that the downregulated proteins are primarily involved in phototransduction, cilium assembly, and photoreceptor cell development. These findings underscore the importance of ribosomal rescue proteins in maintaining retinal health, particularly in photoreceptor cells.